The invention relates to process control. In another aspect, the invention relates to a furnace. In a further aspect, the invention relates to an energy efficient carbon black reactor and its use.
In certain types of furnaces, temperature control is extremely important, as excessive temperatures can damage the furnace. Where the furnace is employed to carry out a process, such as the production of carbon black, the temperature within the furnace is desirably maintained within a relatively narrow range, so as to produce attractive quantities of a desirable product.
A problem which has long existed in the art is that of accurately measuring the temperature within the furnace for control purposes. Conventional temperature sensors cannot long withstand the extremely elevated temperatures encountered in a furnace, typically in excess of 2000.degree. F. Reliable temperature control in a furnace, especially where the characteristics of the air and fuel which are combusted in the furnace are subject to fluctuation, has proved a difficult problem. Fuel characteristics which can vary from time to time include its temperature and composition. Air characteristics which can vary significantly from time to time include its temperature, pressure, and relative humidity.
Especially in processes for the production of carbon black, waste heat which was not utilized in the pyrolysis reaction escapes the furnace in the gaseous effluent. It would be extremely desirable to capture and recycle as much of this waste heat as possible thereby reducing the amount of fuel required to maintain the desired furnace temperature. Due to the high temperatures involved, it would be further desirable to control recycle of heat without undertaking a direct measurement of maximum furnace temperature.